A converging thermal lens is transiently formed by directing a shaped pulsed light beam having at least a first wavelength to a thermo-optic material, whereby the thermo-optic material absorbs the light beam and experiences local heating in response thereto. The heating induces a refractive index profile in the thermo-optic material that temporarily forms the converging thermal lens. In some embodiments, the refractive index of the thermo-optic material has a negative temperature dependence, and the pulsed light beam is shaped to have an inverted light pattern with a maximum intensity in an outer region of the beam cross-section. Alternatively, in some embodiments, the refractive index of the thermo-optic material has a positive temperature dependence, and the pulsed light beam is shaped to have a radially-varying light pattern with a maximum intensity in a central region of the beam cross-section.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An optical system comprising: a first light source providing a focus-activation beam of light having at least a first wavelength; a beam-shaping optical assembly comprising one or more optical components disposed in or along an optical path to a sample, the beam-shaping optical assembly forming the focus-activation beam from the first light source to have a radially-varying light pattern; a thermo-optic material disposed in the optical path before a target portion of a sample, the thermo-optic material absorbing light at the first wavelength, a temperature of the thermo-optic material increasing in response to said absorption; and a transient, converging thermal lens formed in the thermo-optic material by a heating-induced refractive index profile generated by the absorption of the focus-activation beam with the radially-varying light pattern, wherein: a temperature dependence of refractive index of the thermo-optic material is negative, and the radially-varying light pattern is an inverted light pattern having a minimum or zero intensity within a central region and a maximum intensity within an outer region surrounding the central region; or a temperature dependence of refractive index of the thermo-optic material is positive, and the radially-varying light pattern has a maximum intensity within a central region and a minimum or zero intensity within an outer region surrounding the central region.
2. The optical system of claim 1, wherein the beam-shaping optical assembly comprises one or more diffractive optical elements, one or more refractive optical elements, or any combination thereof.
3. The optical system of claim 1, wherein the beam-shaping optical assembly comprises a vortex phase plate, a spatial light modulator (SLM), a digital micromirror device (DMD), or any combination thereof.
4. The optical system of claim 3, wherein the first light source provides the focus-activation beam as substantially monochromatic light having the first wavelength.
5. The optical system of claim 1, further comprising: a second light source providing a probe beam of light having a second wavelength different from the first wavelength, wherein the thermo-optic material absorbs light at the first wavelength different than light at the second wavelength.
6. The optical system of claim 1, wherein: the thermo-optic material comprises a thermal lensing member disposed in the optical path before the sample, the thermal lensing member comprises glass, polymer, ceramic, a container with liquid solution therein, or any combination thereof, and the thermal lensing member has a material composition thereof tailored to absorb light at the first wavelength.
7. The optical system of claim 1, further comprising: an objective lens disposed in the optical path before the sample, wherein the optical system is configured as an optical microscope.
8. The optical system of claim 1, wherein the thermo-optic material comprises a second portion of the sample disposed before the target portion.
9. The optical system of claim 1, wherein the first light source comprises a pulsed laser that outputs a train of optical pulses as the focus-activation beam, and the converging thermal lens is formed in the thermo-optic material by the heating-induced refractive index profile generated by absorption of a single one of the optical pulses of the train.
10. The optical system of claim 9, wherein one or more of the optical pulses has a pulse length less than 500 ns so as to minimize heat diffusion during operation of the thermal lens.
11. A kit for improving resolution of an optical microscope, the optical microscope having an objective lens and a probe beam light source, the kit comprising: a focus-activation light source constructed to provide a beam of light having at least a first wavelength that is different from a wavelength emitted by the probe beam light source; a beam-shaping optical assembly comprising one or more optical components to be disposed in or along an optical path to a sample, the beam-shaping optical assembly being constructed to form the beam from the focus-activation light source to have a radially-varying light pattern; and a thermal lensing member constructed to be disposed in the optical path before the sample, the thermal lensing member being constructed to absorb light at the first wavelength such that a temperature of the thermal lensing member increases in response to said absorption so as to form a transient, converging thermal lens, the thermal lensing member absorbing light at the first wavelength different than light at the wavelength emitted by the probe beam light source, wherein: a temperature dependence of refractive index of the thermal lensing member is negative, and the radially-varying light pattern is an inverted light pattern having a minimum or zero intensity within a central region and a maximum intensity within an outer region surrounding the central region; or a temperature dependence of refractive index of the thermal lensing member is positive, and the radially-varying light pattern has a maximum intensity within a central region and a minimum or zero intensity within an outer region surrounding the central region.
12. The kit of claim 11, wherein the thermal lensing member comprises glass, polymer, ceramic, a container with liquid solution therein, or any combination thereof, and the thermal lensing member has a material composition thereof tailored to absorb light at the first wavelength.
13. The kit of claim 11, wherein the thermal lensing member is substantially transparent to light at the wavelength emitted by the probe beam light source.
14. The kit of claim 11, wherein the beam-shaping optical assembly comprises one or more diffractive optical elements, one or more refractive optical elements, a vortex phase plate, a spatial light modulator (SLM), a digital micromirror device (DMD), or any combination thereof.
15. The kit of claim 11, wherein: the focus-activation light source comprises a laser that outputs a train of optical pulses as the beam, and the focus-activation light source and the thermal lensing member are configured such that a converging thermal lens is formed in the thermal lensing member by a heating-induced refractive index profile generated by absorption of a single one of the optical pulses of the train.
16. The kit of claim 15, wherein one or more of the optical pulses has a pulse length less than 500 ns so as to minimize heat diffusion during operation of the thermal lens.
17. A method comprising: (a) forming a transient, converging thermal lens by: generating a first beam of light having at least a first wavelength; shaping the first beam to have a radially-varying light pattern; and directing the shaped first beam to a thermo-optic material, the thermo-optic material absorbing light at the first wavelength, a temperature of the thermo-optic material increasing in response to said absorption, wherein the thermal lens is formed in the thermo-optic material by a heating-induced refractive index profile generated by the absorption of the shaped first beam with the radially-varying light pattern, and wherein: a temperature dependence of refractive index of the thermo-optic material is negative, and the radially-varying light pattern is an inverted light pattern having a minimum or zero intensity within a central region and a maximum intensity within an outer region surrounding the central region; or a temperature dependence of refractive index of the thermo-optic material is positive, and the radially-varying light pattern has a maximum intensity within a central region and a minimum or zero intensity within an outer region surrounding the central region.
18. The method of claim 17, further comprising: (b) within 10 μs after (a), imaging a sample using at least the converging thermal lens by: generating a second beam of light having a second wavelength different from the first wavelength; using at least the converging thermal lens, focusing the second beam onto a target portion of the sample; and detecting light from the target portion of the sample, wherein the thermo-optic material absorbs light at the first wavelength different than light at the second wavelength, the first beam comprises a train of optical pulses, and the converging thermal lens is formed in the thermo-optic material by the heating-induced refractive index profile generated by absorption of a single one of the optical pulses of the train.
19. The method of claim 17, further comprising: (b) within 1-10 ms after (a), imaging a sample using at least the converging thermal lens by: generating a second beam of light having a second wavelength different from the first wavelength; using at least the converging thermal lens, focusing the second beam onto a target portion of the sample; and detecting light from the target portion of the sample, wherein the thermo-optic material absorbs light at the first wavelength different than light at the second wavelength, and the heating-induced refractive index profile of the converging thermal lens during (b) evolves from heat diffusion within the thermo-optic material.
20. The method of claim 17, wherein the shaping of (a) comprises using one or more diffractive optical elements, one or more refractive optical elements, a vortex phase plate, a spatial light modulator (SLM), a digital micromirror device (DMD), or any combination thereof to shape the first beam to have a light pattern with intensity that varies radially.
21. The method of claim 17, wherein: the thermo-optic material comprises a thermal lensing member that is disposed in an optical path before a sample, the thermal lensing member having a material composition tailored to absorb light at the first wavelength, or the thermo-optic material comprises a portion of a sample before a target portion of the sample.
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April 23, 2021
January 14, 2025
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